Fix workspace factories for workspace token in different scenarios

The following discussion from !205021 (merged) should be addressed:

• @cwoolley-gitlab started a discussion: (+4 comments)

  issue: We should always use let_it_be when possible (https://docs.gitlab.com/development/testing_guide/best_practices/#lets-talk-about-let), unless there's a reason not to (usually due to complex before setup which can interact with let_it_be, which is implmented with before under the covers).

  But I didn't see why it should be necessary here.

  I dug into it for a while, and realized there was an existing bug in this test, because the fixture was getting created with workspace_variable records already associated.

  So, the reason your test was failing was because you were finding the wrong variable record with a nil value (from the original variable creation).

  Below is a patch to fix that.

  issue However, this uncovered another bug in this design. Even with the factory, the default value for the gl_agentw_token variable should never be nil, it should be empty string.

  This is because the factory calls ee/lib/remote_development/workspace_operations/create/workspace_variables_builder.rb directly, but you have added the empty-string-defaulting logic to ee/lib/remote_development/workspace_operations/create/workspace_variables_creator.rb instead of ee/lib/remote_development/workspace_operations/create/workspace_variables_builder.rb

  So, I think the logic for the defaulting needs to be moved to ee/lib/remote_development/workspace_operations/create/workspace_variables_builder.rb instead.

  So, the patch below may only be partially relevant - we should still fix the fixture, but the actual example and test should probably move to the spec for ee/lib/remote_development/workspace_operations/create/workspace_variables_builder.rb instead.

  patch

  Index: ee/spec/lib/remote_development/workspace_operations/create/workspace_variables_creator_spec.rb
  IDEA additional info:
  Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
  <+>UTF-8
  ===================================================================
  diff --git a/ee/spec/lib/remote_development/workspace_operations/create/workspace_variables_creator_spec.rb b/ee/spec/lib/remote_development/workspace_operations/create/workspace_variables_creator_spec.rb
  --- a/ee/spec/lib/remote_development/workspace_operations/create/workspace_variables_creator_spec.rb	(revision b3982bd905d34aeb4dd6806a8b27ffd555c318c4)
  +++ b/ee/spec/lib/remote_development/workspace_operations/create/workspace_variables_creator_spec.rb	(date 1758156868863)
  @@ -12,8 +12,11 @@
     let_it_be(:user) { create(:user) }
     let_it_be(:personal_access_token) { create(:personal_access_token, user: user) }
     # The desired state of the workspace is set to running so that a workspace token gets associated to it.
  -  let(:workspace) do
  -    create(:workspace, user: user, personal_access_token: personal_access_token, desired_state: states_module::RUNNING)
  +  let_it_be(:workspace, refind: true) do
  +    create(
  +      :workspace, :without_workspace_variables,
  +      user: user, personal_access_token: personal_access_token, desired_state: states_module::RUNNING
  +    )
     end
   
     let(:vscode_extension_marketplace) do
  @@ -53,6 +56,12 @@
       described_class.create(context) # rubocop:disable Rails/SaveBang -- this is not an ActiveRecord method
     end
   
  +  it "has fixture sanity check" do
  +    # We must ensure the workspace fixture, which simulates a workspace in the ROP create chain in the process of being
  +    # created, does not contain any pre-existing associated workspace_variable records
  +    expect(workspace.workspace_variables.count).to eq(0)
  +  end
  +
     context "when workspace variables create is successful" do
       let(:valid_variable_type) { RemoteDevelopment::Enums::WorkspaceVariable::ENVIRONMENT_TYPE }
       let(:variable_type) { valid_variable_type }
  @@ -61,8 +70,8 @@
       it "creates the workspace variable records and returns ok result containing original context" do
         expect { result }.to change { workspace.workspace_variables.count }.by(expected_number_of_records_saved)
   
  -      expect(RemoteDevelopment::WorkspaceVariable.find_by_key("key1").value).to eq("value 1")
  -      expect(RemoteDevelopment::WorkspaceVariable.find_by_key("key2").value).to eq("value 2")
  +      expect(workspace.workspace_variables.find_by_key("key1").value).to eq("value 1")
  +      expect(workspace.workspace_variables.find_by_key("key2").value).to eq("value 2")
   
         expect(result).to be_ok_result(context)
       end
  @@ -84,7 +93,7 @@
         it "creates the workspace variable records and returns ok result containing original context" do
           expect { result }.to change { workspace.workspace_variables.count }.by(expected_number_of_records_saved)
   
  -        expect(RemoteDevelopment::WorkspaceVariable.find_by_key(agentw_token_file_name).value).not_to be_empty
  +        expect(workspace.workspace_variables.find_by_key(agentw_token_file_name).value).to match(/glwt-.*/)
   
           expect(result).to be_ok_result(context)
         end